census vs opinion poll

census

noun
  • An official count or enumeration of members of a population (not necessarily human), usually residents or citizens in a particular region, often done at regular intervals. 

  • Count, tally. 

verb
  • To collect a census. 

  • To conduct a census on. 

opinion poll

noun
  • A poll organized in an attempt to quantify public opinion on a subject. 

How often have the words census and opinion poll occurred in a corpus of books? (source: Google Ngram Viewer )